Hello Marlon,

When the XamDataGrid is used without setting a theme (or using its default one), the respective editors for the fields are using an analogical styling as well.
In order to restyle the default look of the editors used for the specific fields (for example the CheckBoxField and the ComboBoxField), you can get the default xaml styles from the DefaultStyles folder from the installation directory of your WPF product (for example: C:\Program Files (x86)\Infragistics\2015.1\WPF\DefaultStyles)  and modify them accordingly.

After that, you can include the files in your project by explicitly referencing them for the XamDataGrid, so they are used.
For more details on restyling the default look of the controls, you can take a look at the following topic.

If you have any questions, please let me know.